Locomotive Boiler Capacity - US vs. German

M Austin · **Joined:** Sat Feb 05, 2005 1:05 am **Posts:** 488

whodom wrote:

But if a Tross stay is less prone to breakage in a small German boiler, shouldn't it make even more sense to apply them to a U.S. boiler that deflects more?

There are 2 different design philosophies at work here.
For example, North American practice recognized the wavy side sheets were unavoidable and used the phenomenon to its advantage reducing staybolt stresses by as much as 40%.

The Germans just lived with it, creating the more flexible Tross staybolt. US practice used the rigid bolts to restrict thermal firesheet expansion reducing staybolt deflection. When the deflection passed the limits where staybolt stress levels became unacceptable, the areas that became known as the "breaking zones", Flannery flexible bolts became the standard.

Review of the "wavy side sheet" thread would be helpful.

mjanssen · **Posted:** Mon Feb 20, 2012 1:16 pm

Matt,

The Tross-Henschel BTH 28 staybolt with an 18mm shaft and 28 mm heads may yield more quickly to bending stress than a plain shaft, 28mm (1 1/8") staybolt in its place. However, it is possible to use the understanding of what Tross was doing to make a staybolt profile which is both rigid and translates some of the bending stress across the shaft to reduce stress near the sheets. It might be just as possible to use the BTH 28 on a tighter pitch, but the 18mm cross section might severely limit the designer's pressure objectives given the staybolt calculations we use in the US.

Matt J.